Finally got that bug!

crudkit/core/spec.py

@@ -1,9 +1,17 @@
+from dataclasses import dataclass
 from typing import Any, List, Tuple, Set, Dict, Optional, Iterable
 from sqlalchemy import and_, asc, desc, or_
 from sqlalchemy.ext.hybrid import hybrid_property
 from sqlalchemy.orm import aliased, selectinload
 from sqlalchemy.orm.attributes import InstrumentedAttribute
 
+@dataclass(frozen=True)
+class CollPred:
+    table: Any
+    col_key: str
+    op: str
+    value: Any
+
 OPERATORS = {
     'eq': lambda col, val: col == val,
     'lt': lambda col, val: col < val,
@@ -68,16 +76,48 @@ class CRUDSpec:
 
         exprs = []
         for col, join_path in pairs:
-            # Track eager path for each involved relationship chain
             if join_path:
                 self.eager_paths.add(join_path)
+
+                try:
+                    cur_cls = self.model
+                    names = list(join_path)
+                    last_name = names[-1]
+                    is_collection = False
+                    for nm in names:
+                        rel_attr = getattr(cur_cls, nm)
+                        prop = rel_attr.property
+                        cur_cls = prop.mapper.class_
+                    is_collection = bool(getattr(getattr(self.model, last_name), "property", None)
+                                         and getattr(getattr(self.model, last_name).property, "uselist", False))
+                except Exception:
+                    is_collection = False
+
+                if is_collection:
+                    target_cls = cur_cls
+                    key = getattr(col, "key", None) or getattr(col, "name", None)
+                    if key and hasattr(target_cls, key):
+                        target_tbl = getattr(target_cls, "__table__", None)
+                        if target_tbl is not None:
+                            exprs.append(CollPred(table=target_tbl, col_key=key, op=op, value=value))
+                            continue
+
             exprs.append(OPERATORS[op](col, value))
 
         if not exprs:
             return None
-        if len(exprs) == 1:
+
+        # If any CollPred is in exprs, do NOT or_ them. Keep it single for now.
+        if any(isinstance(x, CollPred) for x in exprs):
+            # If someone used a pipe 'relA.col|relB.col' that produced multiple CollPreds,
+            # keep the first or raise for now (your choice).
+            if len(exprs) > 1:
+                # raise NotImplementedError("OR across collection paths not supported yet")
+                exprs = [next(x for x in exprs if isinstance(x, CollPred))]
             return exprs[0]
-        return or_(*exprs)
+
+        # Otherwise, standard SQLA clause(s)
+        return exprs[0] if len(exprs) == 1 else or_(*exprs)
 
     def _collect_filters(self, params: dict) -> list:
         """